Willis Appoints Pahl CEO of its German Operation

London, UK, May 1, 2009 — Willis Group Holdings (NYSE: WSH), the global insurance broker, today announced
the appointment of Mathias Pahl as Chief Executive Officer of its German operation, effective May 1,
2009. Pahl will be based in Frankfurt and will report to Adam Garrard, CEO, Willis Continental
Europe. Pahl succeeds Ralf Geck who is retiring.

Pahl has 14 years experience in the insurance industry and has been with Willis since 2003, most
recently as Regional Manager South for Willis Germany. Pahl began his insurance career in 1995 with
Aon Jauch & Hï¿½bener GmbH, where he held a variety of roles including Head of the
International Department for Incoming Business, before moving to Willis.

Commenting on the appointment, Garrard said, “Throughout his time at Willis, Mathias has shown himself to be
a dynamic leader with a strong track record of driving growth. He has proven on countless
occasions that he understands the industry, understands the needs of our clients, and understands the way
Willis works. I am thrilled that the best candidate for this position was within our own
organization, and I am excited at the prospect of working with him in this capacity.”

Willis entered the German market in 1992 and has built up a strong presence in the Property
and Casualty business for large and middle sized corporations. It also has strong specialist expertise in
the areas of Marine, Engineering, Trade Credit, Fine Art and M&A. Willis Germany has more than
350 Associates nationally, working in offices in Frankfurt, Cologne, Munich, Hamburg, Stuttgart, Bremen, Bielefeld and Hannover.

Willis Group Holdings Limited is a leading global insurance broker, developing and delivering professional insurance, reinsurance, risk
management, financial and human resource consulting and actuarial services to corporations, public entities and institutions around
the world. Willis has more than 400 offices in nearly 120 countries, with a global team
of approximately 20,000 Associates serving clients in some 190 countries. Additional information on Willis may be
found at www.willis.com.